Articulated assembly of solar generator panels and space vehicle

ABSTRACT

The invention relates to an articulated assembly ( 1 ) comprising at least two panels ( 4 - 7 ) which are positioned close to a solar generator. The aforementioned panels are articulated in pairs such they can pivot between a stacked configuration, in which the panels are stacked on top of one another, and an unstacked or deployed position, in which the panels are disposed essentially in one plane, said panels being interconnected by means of a hinge. According to the invention, the hinge element is formed by at least one Carpentier coupling ( 11 ) which performs the following two functions: (i) in the stacked configuration and during deployment, the coupling generates a permanent driving torque which moves the panels into the unstacked configuration; and (ii), in the unstacked configuration, the coupling provides a mechanical restraint for the panels.

The present invention relates generally to the deployment of solargenerator panels of a space vehicle, such as a satellite in orbit aroundthe Earth, although this is not limiting on the invention.

In the present context, the expression “solar generator panel” means allthe plane structures of the solar generator having active optical,thermal or photovoltaic surfaces, and in particular:

-   -   support panels of an array of identical or different        photovoltaic cells for converting solar energy into electrical        energy;    -   reflector panels that concentrate solar radiation onto the above        panels thanks to a coating with appropriate properties;    -   panels used for their surface thermo-optical characteristics        (heat dissipation).

The panels of a solar generator may be arranged in highly diverseconfigurations. Conventionally there is a longitudinal successionparallel to a direction away from the body of the space vehicle andabout which the generator is adapted to turn to track the sun. However,to increase the available electrical power, it has been proposed toprovide lateral panels in addition to the panels previously referred to.Also known in the art are configurations in which the panels aredisposed in a transverse direction, i.e. in a direction transverse tothe aforementioned longitudinal direction in which extends the yoke orspacer arm that connects the generator to the body of the space vehicleand about which the generator is adapted to turn to track the Sun.

During launch, the generator is folded and its panels are stacked one onthe other in a configuration known as the stacked or stackingconfiguration.

Putting the generator into operational service, for example when thevehicle is a satellite that has been placed in its service orbit,entails unfolding the stack of panels: this is referred to asunstacking.

To go from the stacking configuration to the deployed configuration inwhich the solar panels are disposed in substantially the same plane, thepanels are hinged in pairs, either by means of joints having adjacentelements hinged about a pivot axis and each fastened to one of twoadjacent panels, or by means of joints connecting parallel edges of thepanels.

The first joints cited above are generally used to connect the panels ofthe longitudinal succession cited above (in-line panels), whereas thesecond joints cited above are generally used to connect the lateralpanels to the in-line panels.

Generally speaking, the joints currently used for solar panels arecharacterized by the existence of friction between the parts in contact.Such joints necessitate lubrication, which is very difficult to providegiven the extreme conditions of temperature and vacuum to which thesatellite is subjected during launch and after it is placed in orbit.Under these conditions, materials tend to weld together spontaneously orto bind, with the risk of non-deployment of the panels.

Furthermore, the current joints generally deploy the panels by means ofa specific drive system. The high and dispersed friction in the jointsnecessitates a powerful drive system.

Moreover, to lock the in-line panels in the deployed configuration, thepanel joints are generally provided with a locking mechanism includingrotary locking means mounted on a first of two adjacent elements andcooperating with the second of the two adjacent elements to lock thecorresponding two panels in their deployed configuration. The lockingmeans are constrained to rotate with a lug rotatably mounted on thefirst of the adjacent elements and temporarily locked against rotationby being abutted against a peripheral surface of an element constrainedto rotate with the second of the two adjacent elements. The peripheralsurface has a configuration such that when the corresponding two panelsreach the deployed configuration the lug escapes from the peripheralsurface and pivots to bring the locking means into contact with thesecond of the two adjacent elements in order to lock the two panels inthe deployed configuration.

Such joints represent a mass penalty for the satellite.

An objective of the invention is therefore to provide a hinged set ofsolar generator panels whose mass does not penalize the mission byminimizing the number of mechanical elements without compromising thestorage and deployment functions or the mechanical strength of thepanels in the unstacked configuration.

To this end, the invention consists in a hinged assembly formed of atleast two adjacent panels of a solar generator hinged in pairs to pivotfrom a stacking configuration, in which the panels are stacked one onthe other, to an unstacking or deployed configuration, in which thepanels are disposed substantially in the same plane, the two panelsbeing connected together by at least one hinge,

characterized in that said hinge is formed of at least one Carpentierleaf spring joint having the dual function of:

in the stacking configuration and in the deployment phase, generating acontinuous driving torque tending to move the panels toward theunstacking configuration, and

in the unstacking configuration, mechanically retaining the panels inthat configuration.

Thus the hinged assembly of panels according to the invention has amechanical panel hinge structure that is optimized in terms of its mass.

It is therefore possible to deploy in-line and/or lateral panels underkinematic conditions such that a panel is opened spontaneously, withoutadditional drive means, thanks to a simple and light mechanical devicehaving the advantages referred to above, namely a Carpentier joint.

It is important to note that a system of the above kind could ifnecessary be transposed to the deployment of in-line or lateral panelswith respect to each other, for example.

According to one embodiment of the invention, said hinges between twoadjacent panels are formed only of Carpentier joints.

According to one embodiment of the invention, said Carpentier jointsextend under the panels that they connect.

According to one embodiment of the invention, the plurality ofCarpentier joints forming the connection between two adjacent panels isadapted to feature a crossed succession of Carpentier joints adapted togenerate opposite driving torques as a result of folding the twoadjacent panels.

According to one embodiment of the invention, the routing of the powercurrent between panels is effected by a wiring harness using a materialhaving the same mechanical properties as a Carpentier leaf spring.

The deployment of the panels is usually sequenced electrically, usingpyrotechnic devices, such as pyrotechnic shears, to release palletsretaining the panels in the stacking configuration. To this end, at theappropriate time, the pyrotechnic devices break tie-rods retaining theretaining pallets, which releases the panels to move from the stackingconfiguration to the unstacking configuration.

According to one embodiment of the invention, the vehicle includespallets for retaining the panels in the stacking configuration and, whenthe panels are in the stacked configuration, said pallets lie in planesparallel to those of the panels, each pallet being connected to a fixedstructure of the vehicle by at least one Carpentier joint adapted toexert a driving torque tending to move the pallet out of the paneldeployment space.

According to one embodiment of the invention, the geometry and the areaof the pallets are chosen so that, when in the stacked configuration,the pallets cover only part of the surface of the upper panel.

The invention also consists in a space vehicle, in particular asatellite, characterized in that it includes a hinged assembly accordingto the invention.

The present invention is described in more detail next with reference tothe appended drawings, in which:

FIG. 1 represents a satellite wing including a hinged set of solarpanels in an unstacked configuration conforming to one embodiment of theinvention,

FIG. 2 represents the satellite wing in the stacked configuration insection taken along the line A-A in FIG. 1, and

FIG. 3 represents the satellite wing in section taken along the line C-Cin FIG. 2.

In the present application, elements having similar functions carryidentical reference numbers.

FIGS. 1 to 3 show diagrammatically a small part of a hinged assembly 1formed of four panels forming part of a solar generator.

For clarity, the remaining panels of the solar generator and theremainder of the satellite itself are not shown in the figures.

The hinge assembly 1 is connected to a mechanism 2 for rotating theassembly by means of a yoke 3.

The assembly 1 includes four rigid deployable panels numbered 4 to 7 inthe figures.

The panels are hinged in pairs in order to be able to pivot from astacking configuration represented in FIGS. 2 and 3, in which the panelsare stacked one on the other, to a deployed configuration represented inFIG. 1, in which the panels are disposed in substantially the sameplane.

In the embodiment described with reference to FIGS. 1 to 3, the panels 4to 7 are adapted to form a longitudinal succession of in-line panels.They are hinged together in pairs by means of Carpentier joints 11, eachof which is fastened on each side to one of two parallel edges ofadjacent panels. As explained hereinafter, these Carpentier joints 11have a “self-driving” effect that deploys the panels that they connect,and there are three of them for each pair of parallel edges.

Of course, this number of joints is in no way limiting on the invention.

The person skilled in the art uses the term “Carpentier joint” to referto the principle of mechanical driving and locking associated with aleaf spring. Accordingly, the use hereinafter of the term “Carpentierjoint” refers to the use of a leaf spring alone, without any additionalmechanical means, with the possible exception of means for fixing theleaf springs to the panels or to thin film cells.

It must be clearly understood that the leaf springs are the onlyelements joining two panels. It is in this respect that the invention isbeneficial, self-driving and locking functions being provided by thesame compact element.

In FIGS. 2 and 3, the panels stacked one on the other are retained inthe stacked configuration by pallets 8 that are themselves held in thisposition by tie-rods 9 fixed to a fixed structure of the satellite (notshown). In this latter position, the Carpentier joints form an elbowprofile 110 at each bend, compressed by the retaining pressure of thepallets. The Carpentier joints 10 therefore work in flexion and atraction force is applied to the pallets.

To trigger the deployment of the panels, the tie-rods are broken bypyrotechnic shears (not shown). As a result, because of the Carpentierjoints 10 connecting the pallets to the structure, the pallets aredriven in rotation through 90°, moving the pallets out of the field ofdeployment of the panels.

At this moment, when the retaining pallets are released, the drivingtorque stored in the Carpentier joints 11 automatically deploys thepanels, as shown in FIG. 1. Once in the unstacked configuration, theCarpentier joints are perfectly straight and lock the panels in thisposition.

According to one embodiment of the invention, the plurality ofCarpentier joints forming the connection between two adjacent panelsfeatures a crossed succession of Carpentier joints 11 and 11′ so thatopposite driving torques are developed upon folding two adjacent panels.

Note that the geometry and the area of the pallets is chosen so thatthey cover only part of the surface of the upper panel 4. Thissignificantly reduces the inertia of the wing.

The panels include solar cells, preferably cells employing thetechnology known to the person skilled in the art as the “thin film”technology. According to one advantageous aspect of the invention, thepanels include thin film cells and there is no interleaved protectivefilm between the facing panels in the stacked configuration.

According to a highly advantageous variant of the invention showncross-hatched in FIG. 1, three Carpentier leaf springs 111-113 passthrough the wing along the main deployment axis of the wing, merging atthe joints 11, 11′. This achieves the advantage referred to hereinaboveof providing the Carpentier joint function at the hinges 11, 11′ and theadditional function of supporting the “thin film” flexible substrate.

According to another advantageous embodiment of the invention, currentis routed between the panels by a wiring harness using a copper alloy ofthe CuBe type having the same mechanical properties as a Carpentier leafspring.

1. Hinged assembly (1) formed of at least two adjacent panels (4-7) of asolar generator hinged in pairs to pivot from a stacking configuration,in which the panels are stacked one on the other, to an unstacking ordeployed configuration, in which the panels are disposed substantiallyin the same plane, the two panels being connected together by at leastone hinge, characterized in that said hinge is formed exclusively of aCarpentier leaf spring joint (11) having the dual function of: in thestacking configuration and in the deployment phase, generating acontinuous driving torque tending to move the panels toward theunstacking configuration, and in the unstacking configuration,mechanically retaining the panels in that configuration, and in thatsaid Carpentier leaf spring joint extends under the panels that itconnects to form the support structure thereof.
 2. Assembly according toclaim 1, characterized in that the plurality of Carpentier leaf springjoints forming the connection between two adjacent panels provides acrossed succession of Carpentier leaf spring joints (11, 11′) togenerate opposite driving torques upon folding the two adjacent panels.3. Assembly according to claim 1, characterized in that power current isrouted between panels by a wiring harness using a material having thesame mechanical properties as a Carpentier leaf spring joint. 4.Assembly according to claim 1, characterized in that the vehicleincludes pallets (8) for retaining the panels in the stackingconfiguration and in that, in the stacked configuration, said palletslie in planes parallel to those of the panels, each pallet beingconnected to a fixed structure of the vehicle by at least one secondCarpentier leaf spring joint (10) adapted to exert a drive torquetending to move the pallets out of the panel deployment space. 5.Assembly according to claim 4, characterized in that the geometry andthe area of the pallets is chosen so that, when in the stackedconfiguration, the pallets cover only part of the surface of the upperpanel.
 6. Space vehicle, in particular satellite, characterized in thatit includes a hinged assembly according to claim 1.